ScriptingText Ascii Art to 3d Text Mesh - Ways to preserve spaces when converting txt to 3d Object
You need to set the font to a monospaced font.  BFont is proportional and so the characters are different sizes.

I used Consolas which is a monospaced font, and the text is exactly as it looks in the editor.  I believe Consolas ships with Windows.

This is with the default BFont: